[PATCH 2/5] cpufreq: governor: Check transition latecy at init time only

From: Rafael J. Wysocki
Date: Fri May 13 2016 - 18:59:45 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

It is not necessary to check the governor's max_transition_latency
attribute every time cpufreq_governor() runs, so check it only if
the event argument is CPUFREQ_GOV_POLICY_INIT.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -2011,23 +2011,24 @@ static int cpufreq_governor(struct cpufr
if (!policy->governor)
return -EINVAL;

- if (policy->governor->max_transition_latency &&
- policy->cpuinfo.transition_latency >
- policy->governor->max_transition_latency) {
- struct cpufreq_governor *gov = cpufreq_fallback_governor();
+ if (event == CPUFREQ_GOV_POLICY_INIT) {
+ if (policy->governor->max_transition_latency &&
+ policy->cpuinfo.transition_latency >
+ policy->governor->max_transition_latency) {
+ struct cpufreq_governor *gov = cpufreq_fallback_governor();

- if (gov) {
- pr_warn("%s governor failed, too long transition latency of HW, fallback to %s governor\n",
- policy->governor->name, gov->name);
- policy->governor = gov;
- } else {
- return -EINVAL;
+ if (gov) {
+ pr_warn("%s governor failed, too long transition latency of HW, fallback to %s governor\n",
+ policy->governor->name, gov->name);
+ policy->governor = gov;
+ } else {
+ return -EINVAL;
+ }
}
- }

- if (event == CPUFREQ_GOV_POLICY_INIT)
if (!try_module_get(policy->governor->owner))
return -EINVAL;
+ }

pr_debug("%s: for CPU %u, event %u\n", __func__, policy->cpu, event);